fix(hotfix): v3.13.1 — fix ImportError in api_list_sites (My Sites broken)

routes.py still imported MAX_SITES_PER_USER from core.site_api which was
removed in v3.13.0. This caused 500 errors on /api/sites, making My Sites
appear empty for all users. Fixed to use get_cached_max_sites().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

core/dashboard/routes.py

@@ -5126,14 +5126,16 @@ async def api_list_sites(request: Request) -> Response:
     if redirect:
         return JSONResponse({"error": "Unauthorized"}, status_code=401)
 
-    from core.site_api import MAX_SITES_PER_USER, get_user_sites
+    from core.settings import get_cached_max_sites
+    from core.site_api import get_user_sites
 
     sites = await get_user_sites(user_session["user_id"])
+    limit = get_cached_max_sites()
     return JSONResponse(
         {
             "sites": sites,
-            "limit": MAX_SITES_PER_USER,
-            "remaining": max(0, MAX_SITES_PER_USER - len(sites)),
+            "limit": limit,
+            "remaining": max(0, limit - len(sites)),
         }
     )